"Wetback is a derogatory term used to describe Mexicans who have immigrated illegally to the United States by swimming or wading across the Rio Grande--the river that separates the U.S. from Mexico. U.S. Border Patrol began using the word in 1944 to refer to illegal Mexican immigrants who were easily identifiable by their wet clothing.
In 1954, the U.S. Immigration and Naturalization Service made the word "wetback" official by naming the mission to remove illegal immigrants from the United States, Operation Wetback . In response to the increase of immigrants during the early 1950s, the agency developed the program to force immigrants (particularly Mexicans) back to their home countries. Aproximately one million Mexican Americans were deported in one year.

Today the term "wetback" is often used to express animosity towards Central American or Latin American immigrants--legal and illegal--who do not speak English. Meanwhile, in an attempt to reclaim the word, some Mexican-Americans call themselves Los Mojados, meaning "the wet ones."

~ This definition courtsey of www.gurl.com

Ted : Damn wetback !

Ed : Take it easy, man. He came over here as a baby on his mother's back. It's not his fault.

Originally a nick name for Mexicans greaser, beaner, pepper belly, either legally or illegally in the country. Originated in the American Southwest border states, Texas, New Mexico, Arizona, and California. Through common usage has come to mean citizens of any nation who have immigrated here illegally.

Term used to describe the majority of Mexicans in the USA that come here illegally. They can be characterized as being dirty, rude, and completely unwilling to learn any English. They also protest to our government, because they feel, for some reason, that the USA owes illegals something. They pay no taxes, collect free health care, and are just a general leech on our country as a whole.

I cant get medical care for my family, but those wetbacks, get it for free.